A semiconductor memory device is a memory device which is fabricated using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), and the like. Semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
The volatile memory devices may lose stored contents at power-off. The volatile memory devices include a Static RAM (SRAM), a Dynamic RAM (DRAM), a Synchronous DRAM (SDRAM), etc. In contrast, the nonvolatile memory devices may retain stored contents even at power-off. The nonvolatile memory devices include a Read Only Memory (ROM), a Programmable ROM (PROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable and Programmable ROM (EEPROM), a flash memory device, a Phase-change RAM (PRAM), a Magnetic RAM (MRAM), a Resistive RAM (RRAM), a Ferroelectric RAM (FRAM), etc.
Recently, storage media has been developed that uses a nonvolatile memory instead of a hard disk. While an operation speed of storage media that utilizes nonvolatile memory is faster than that of the hard disk, the speed of an interface between a host and the storage media may be a limiting factor. For this reason, the nonvolatile memory may use a buffer memory for compensating for a slow interface speed. The buffer memory is used to store data temporarily and communicates with the host and the storage media through a direct memory access operation.